The environment in ports all over the world is becoming more and more of an issue. In the last 15 years, increasing attention has been paid on how to reduce pollution coming from the diesel engines of ships which traffic, in ever increasing numbers, the ports and terminals. Container, RoRo (roll-on/roll-off), cruise or other M/V (motorized vessel) ships often remain docked in a port for several days and keep their engines running while docked to ensure the functioning of refrigerated containers and life aboard the ship through air-conditioning, controls, etc. It is clear that this constitutes an important pollution issue, which has to be avoided. It has therefore been proposed to supply power to such ships via cables running from the dock to the ship, thereby allowing the engines to be turned off.
One problem with supplying such docked ships with power is the need for a high voltage and high amperage power supply, which has often made it necessary to use up to 10 cables in parallel. Due to this large number of cables it was not possible to connect and disconnect rapidly and safely, not to mention that they also had to cope with uneven loads between the cables. Also, the amount of cables was rather untidy and also dangerous. Furthermore, it is often not possible to align the ship-based power inlet with the dock-based power supply, which means that the cables run alongside the ship either on the dock or on the deck of the ship, causing further obstruction and danger.
The wharf or dock is generally supplied with 6600 V and a significant part of the current shipping fleet is supplied with between 230 V and 660 V, hence the necessity for using step-down transformers and/or converter sets.
A maritime power supply (MPS) system has been proposed wherein a cable management system having a cable reel with a power cable assembly mounted thereon is provided. Such a cable management system can be mounted on the ship, wherein one end of the power cable assembly on the cable management system is connected to a ship-based power inlet. The opposite end of the power cable assembly can be unwound from the cable management system and lowered onto the dock for connection to a dockside power supply. Since the voltage, frequency and amperage of the dockside power supply do not necessarily correspond to the ship's needs, a step-down transformer and/or converter has to be installed between the dockside power supply and the ship-based power inlet.
One problem associated with such systems is that the power cable assemblies are rather heavy and are therefore not easy to lower down to the dockside power supply. More importantly, such power cable assemblies may be damaged if they are repeatedly dragged along the floor, and in particular when dragged over the edge of the ship.
One solution is to use lifting equipment, such as a crane or the like, to lower the power cable assembly to the dockside power supply. A drawback of this solution it that such lifting equipment is not always available and that it does not efficiently prevent the power cable assembly from rubbing on the edge of the ship.